Thank you for contacting us. What's happening here is that you have already set up an mSecure 5 account, and that account has a different password securing it than the password you are using in mSecure 4.5.4, which is not uncommon. In order to fix this, you will have to reset the mSecure 5 account, because there is no way to bypass this part of the process when signing in to the app.
Before I help you with that can, can you let me know if you have entered much, if any, data into mSecure 5 in the past? Also, do you have access to all of your information in the mSecure 4.5.4 app? If so, it will be easiest to simply reset your mSecure account and the app on your device(s), then you can sign in to your account and restore from a backup made in mSecure 4.5.4.
It's good to hear everything is working on your iOS device! As long as all your data is available in mSecure 5, you should have no problems on your PC and Chrome Book. Do be aware you will need to download the app from the Play Store on the Chrome Book, since it runs Android apps. Also, you will need to authenticate as the owner of the account on the other device using the QR code you will find the account settings of mSecure on iOS. You can follow the steps laid out in this article for instructions if needed: Account Authentication